Mark M. answered 07/30/20
Retired math prof. Very extensive Precalculus tutoring experience.
sinA / a = sinB / b
So, sin57° / 11 = sinB / 13
sinB = 0.9912
Sine is positive in quadrants 1 and 2, so there are 2 possibilities.
B = Sin-1(0.9912) or 180° - Sin-1(0.9912) = 82.4° or 97.6°
There are two triangles.